1. Technical Field
The invention generally relates to electronic music controllers, and more particularly to position correction for electronic musical instruments.
2. Related Art
Continuous-pitch electronic controllers are a promising alternative to traditional electronic music keyboards for controlling music synthesizers. Continuous-pitch controllers allow the musician to use any tuning system, to play vibrato and smooth glissandi, to play blue notes, and to perform many other expressive actions not possible on a traditional music keyboard. A variety of continuous-pitch electronic controllers are commercially available. Monophonic controllers include MIDI Theremins, MIDI ribbon controllers, and the KYMA-WACOM controller. Polyphonic controllers include the Tactex Multitouch and the Haken Audio™ Continuum™ Fingerboard. The Continuum™ Fingerboard is discussed in U.S. Pat. No. 6,703,552, which is incorporated herein by reference. Experimental controllers include the Fretless MIDI Guitar and the MIDI Trombone.
Continuous-pitch controllers rely on a skilled musician that has developed precise positioning techniques. Precise positioning of either the hand (for the Theremin), finger (for ribbon controllers, the Tactex controller, the Continuum™ Fingerboard, and the Fretless MIDI Guitar), pen (for KYMA-WACOM), or slide (MIDI Trombone) is essential for a good performance. As used herein, “finger” should be understood to mean a hand finger, pen, slide, or other control mechanism used to identify a position that corresponds to a desired musical parameter. “Finger position” is a position on the playing surface of the electronic music instrument or controller. For example, the finger position may identify a pressure focal point on a Continuum™ Fingerboard and may correspond to a desired pitch. “Finger position data” should be understood to mean data that identifies a finger position.
Continuous-pitch instruments provide new possibilities for the performing musician, but also present added difficulties. The musician must precisely place fingers for an in-tune performance. This can be challenging, especially for polyphonic controllers, which must address several notes played at once. Not only must each finger be placed in the exact position at the beginning of each note; each finger must be in exact position after glissandi and other finger movements are performed. If the continuous controller has an octave spacing comparable to a traditional music keyboard, finger positions must be accurate to a fraction of a millimeter (3 to 5 cents) to satisfy a sophisticated listener.
Accordingly, it is desirable to include pitch correction in the controller. A variety of methods exist for modify the pitch of notes in audio recordings. For example, an audio waveform may be analyzed and modified to change the frequency of the fundamental and harmonics of a note. This is technically challenging, however, and existing algorithms have a varying degree of success dealing with polyphony, reverb, and timbre artifacts introduced in changing the waveform.
Alternatively, one can correct finger position, instead of waveform. In this manner, correction can be accomplished before a waveform is generated. One method is to round the value to correspond with the nearest MIDI key number. Simple rounding to the next MIDI key number, however, transforms the continuous pitch instrument into a discrete pitch instrument. Accordingly, devices using such a method are not able to perform vibrato, smooth glissandi, or any of the other small variations in pitch.
Further developments have implemented finger position correction in which the initial finger position is rounded to the nearest MIDI key number, and then pitch changes are tracked from that position. Such a feature has been available in the Haken Audio™ Continuum™ Fingerboard since 2001.
As one advantage of continuous pitch devices is the incorporation of smooth glissando and/or vibrato, it would be beneficial to implement a controller, continuous-pitch or otherwise, that will correct finger positions continually, i.e. not only at the beginning of a note, and will allow for glissando and vibrato.